1. Field of the Invention
The invention relates generally to the field of magnetically released security devices. More specifically, the invention relates to magnetic decouplers that are usable with more than one type of magnetically releasable security device.
2. Background Art
There are various magnetically releasable security (antitheft) devices known in the art that are lockably coupled to an article to affix a surveillance tag to the article. The antitheft device is typically released from the article at the point of sale by using a magnetic decoupler. The most commonly used antitheft device is called a “hard tag.” See, for example, U.S. Pat. No. 4,339,853 issued to Lipschitz. More recently, a double-pin or “double clutch” hard tag has been developed that requires a magnetic field with a greater longitudinal span than the single clutch or single pin hard tag. Examples of magnetic decouplers that can operate single clutch devices are shown in U.S. Pat. Nos. 5,959,520 and 6,084,498 issued to Stelter et al. and assigned to the assignee of the present invention.
Another widely used antitheft device is the “keeper box” used for CD/DVD, software and games. The keeper box requires a much wider magnetic field region to unlock. See, for example, U.S. Pat. No. 6,832,498 issued to Belden, Jr. et al. The field direction is horizontal, unlike the field for a typical hard tag, which is in the vertical direction with respect to the pin that locks the device to the article. Another example of a security device requiring a transverse magnetic field to decouple is shown in U.S. Patent Application Publication No. 2007/0067971 filed by Nguyen et al.
Typically, each type of antitheft device requires a specific type of magnetic field profile to release the device from the article. The point of sale operator would therefore require various types of magnetic decouplers for use with the various antitheft devices.
There is a need for a multifunction magnetic decoupler that is operable with various antitheft devices.